Hollow metal is a type of defect found in metal interconnects of microelectronic devices. Hollow metal refers to voids at the surface of the metal line. The voids are detected after polishing the metal. Accordingly, hollow metal voids are different from voids formed by electromigration or stress migration because an interconnect having hollow metal has not experienced electric current or substantial heat cycles, respectively.
Void defects such as hollow metal are detrimental to both device performance, leading to electrical opens and reliability degradation, and manufacturability. Therefore, it is desirable to repair the defects.